Donald L.Sparks is S.Hallock duPont Chair of Environmental Soil Chemistry and Francis Alison professor at the University of Delaware at Newark. He also holds joint faculty appointments in the Departments of Civil and Environmental Engineering and Chemistry and Biochemistry in the College of Marine Studies. Dr. Sparks is internationally recognized for his research in the areas of kinetics of soil chemical processes, surface chemistry of soils and soil components using in situ spectroscopic and microscopic techniques, and the physical chemistry of soil potassium. He is the recipient of many awards and honors, including being named a fellow of the American Society of Agronomy, the Soil Science Society of America, and the American Association for the Advancement of Science. He is a past-president of the Soil Science Society of America and is currently president-elect of the International Union of Soil Science. Dr. Sparks received his M.S. in soil science from the University of Kentucky and his Ph.D. from the Virginia Polytechnic Institute and State University.

Robert C.Spear is professor of environmental health sciences in the School of Public Health at the University of California at Berkeley. He is also the founding director of the university’s Center for Occupational and Environmental Health. His research interests include the mathematical modeling of toxicological and infectious disease processes and statistical issues in exposure assessment. Dr. Spear has an extensive publication record in this field, spanning farm workers’ exposures to pesticides to strategies for the characterization and control of the exposure of rural populations to parasites in the developing world. He has also served on a number of scientific advisory committees, including the Board of Scientific Councilors of the National Institute for Occupational Safety and Health. Dr. Spear received his B.S. and M.S. in mechanical engineering from the University of California at Berkeley, and his Ph.D. in control engineering from Cambridge University.